of toledo



April 24, 1928.

J. L. DRAKE SHEET 0F GLASS AND PROCESS OF PRODUCING THE SAME Filed March 2'7v 1926 I zlwuqmtoz (John L .DFO/TGL, M 5

Patented Apr. 24, 1928.

' UNITED STATES 1,667,146 PATENT OFFICE.

JOHN L. DRAKE, OF TOLEDO, OHIO, ASSIGN OR TO THE LIBBEY-OWENS SHEET GLASS COMPANY, OF TOLEDO, OHIO, A CORPORATION OF OHIO.

SHEET or GLASS AND rnoosss or PRODUCING THE SAME.

Application filed March 27, 1926. Serial no. 97,900.

The present invention relates to sheet glass, and to an improved process for producing the same.

An important object of the invention is to provide an improved process adapted for the-production of a new article of manufacture, namely, a sheet of ground and firepolished glass.

"Another object of the invention is to pro videa process wherein a sheet of glass may be ground and then fire-polished. A further object ofthe invention is to provide a processwherein a sheet of glass may be formed, afteiywhich' the surfaces thereof may be ground the ground sheetbeing reheated and then subjected to a flame to fire-polish the ground surfaces, the sheet then being slowly reduced to room temperatures.

Other objects and advantages of the invention will become apparent during thefollowing description.

' In the drawings wherein like numerals are employed to designate like parts throughout the same,

Fig. 1 is a diagrammatic View illustrating a sheet being ground and reheated,

Fig. 2 is a sectional View showing diagrammatically the end of the reheating means, the fire-polishing of the sheet, and the starting of the cooling operation, and

Fig. 3 is a diagrammatic view illustrating the exit of the sheet after it has been cooled.

The present invention relates particularly to the production of so-called plate glass.

wherein glass blank is ground and polished in a manner that the surfaces of the sheet are substantially flat and parallel, thus reducing to a. minimum distortion of vision therethrough. It has been customary heretofore in the production of sheet glass to grind a blank and then polish the same by a rubbing action of a suitable polishing compound such as rouge applied by means of a felt pad.

In the present invention the grinding is accomplished by any of the well known methods now in vogue, while the polishing is accomplished by means of a flame or fire, giving the sheet what is known as a the polish. By grinding the sheet prior to ts polishing, in accordance with the present Invention, all surface defects are removed so that a ground blank is produced having flat surfaces and a sheet of uniform thickncss. y

In the drawings the numeral 5 designates d:agrannnatically a sheet glass grinding inaclnne. By means of the grinding head 6 the sheet 7 may be ground on both of its surfaces by grinding first one side and then turning the sheet over and grinding the sccond side.

After the sheet has been ground on both sides it may then be. passed through a reheat ing chamber 8. The chamber 8 preferably includes a plurality of rotatable rolls adapted to support the sheets 7 in their passage through said chamberfl Suitable heating means 10 may be used to gradually elevate the temperature ofgthe glass sheets. The sheet, after it has becomesuita-bly heat-- ed, may then pass upon a moving table. 11, where it is subjected to the action of a flame 12 of suflicient intensity to produce what is known in the art as a fire-polish upon the ground surface of the sheet 7; The fiameis preferably what may be called a sharp flame adapted to lick the surface of the sheet so that it will polish the surface of the sheet of glass with which it contacts without destroying the uniformity of thickness of thesheet. By using this type of flame the very surface of the sheet can be melted so to speak, without causing a breakdown of the body of said sheet. Of course, the melting referred to is sufficient to cause fire polishing of the ground-surfaces. One or a plurality of flames 12 may be applied to the sheet as desired. After one side of the sheet has been fire-polished. it may be reversed as indicated at 13, and the second side of the sheet may be fire-polished as by means of the flame 14:. The table .r

ll, supported upon the means 15. may be housed by means of a cover 16, and any suitable turnover device may be used to turn the sheet 7 after one side has been polished. After the second side of the sheet has been polished, it is then passed through a cooling chamber 17. This chamber preferably includes rotatable supporting means 18 and heating means 19, whereby the sheet is gradually reduced to room temperatures. After the sheet has been cooled, it is passed out upon a table 20, from where it may be removed and examined as desired.

Of course, it is to be understood that the sheet 7 is annealed prior to the grinding operation. In other words, the sheet or blank 7 is produced in the customary manner including the ordinary annealing operation. The cooling chamber 17 is used to bring the heated sheet 7 to room temperatures after it has been fire-polished. It is not absolutely necessary to reheat the sheet 7 before it is firepolished, but the danger of breakage. is considerably lessened if it is reheated. I It is well. known in the art that a the polish or a' fire finish has more luster than the finish sometimes produced by a rubbing action. A piece of plate glass produced by the. above described apparatus can be made much more cheaply than with the rubbing process. V

Ofcourse both surfaces oil, the sheet may be fire-polishedsimultaneously by moving the same onspaced rolls and applying a flame on both. of the surfaces by arranging them. above. and below the sheet.

It is to be understood thatthe form of the invention herewith shownaand described is to. be taken as the preferred GHIbOCllIfiGDi] of the same, and that various changes in the shape, size and arrangement of parts may be resorted to Without departing from the spirit of the invention or the scope of the subjoined claims.

I claim: p

1. The process of producing a transparent sheet of glass, consisting in grinding a sheet of glass, and then fire-polishing the same.

2; The process of producing plate glass, consisting in grinding both sideso'f a sheet of glass, and. then fireepolishing the same.

3. The process of finishingsheet glass, consisting in grindinga sheet of glass, heating thesaine, and then polishing said sheet.

4. The process of finishing sheet glass,

consistlngin grindinga sheet or glass, heating; the same, and then firepolishing said sheet.

5. The process of finishing a sheet of glass, consisting in grinding the sheet, then 9. The process of producing polished sheet glass, consisting 1n grinding the surfaces of a sheet of glass, gradually elevating the ten'iperature of said sheet, then subjecting the heated ground surfaces to the action of a tlame'to firepolish the same.

10. The process of producing polished sheet glass, consisting in grinigling the surfaces oi? a sheet of glass, gradually elevating the temperature of said sheet, subjecting the heated ground surfaces to the action of a flame to fire-polish the same, and then cooling said sheet.

ll. The process of producing polished sheet glass, consisting in grinding both surfaces of a sheet of lass assin the round D 7 c: t:

sheet through a heating chamber, lire-polish- 111g one side of the sheet, then turning the sheet over and fire-polishing the second 1 side, and-then coolingsaid sheet.

12. As a new article of manufacture, a sheet. of glass Whichhas been ground, reheated and fire-polished.

13. As a new article of manufacture, a sheet of glass which has been ground and fire-polished.

Signed at Toledo, in the county of Lucas and State of Ohio, this 25th day of March, 1926.

JOHN L. DRAK 

